After her mother’s death, junior high student Yoshiyama Kazuko lives in Yokohama with her father and little sister. One summer night, while stargazing with her childhood friend Goro and little sister Non-chan, they meet Kazuo, a mysterious young man in uniform who seems oddly familiar. After inhaling a lavender-scented mixture in a lab accident, Kazuko gains psychic powers, enabling her to time leap. Her strange experiences lead her closer to a shocking truth—Kazuo is a time traveller from the 27th century. He warns her that hearing the sound of something breaking triggers her time travel, but leaping into the past or future more than a day could bring dire consequences. A feisty Kazuko never bothers; she makes use of her abilities to help those around her until the ultimate price is paid. Her relentless kindness costs her the one person she loves most: her little sister, Non-chan.